This trying to get the club into certain positions on the backswing is a load of rubbish as Jim Furyk, Lee Trevino and others will attest to. You don’t hit the ball on the backswing and they hit the ball pretty good on the downswing. Quite a lot of instructors today are teaching a flatter downswing as the way to go. You sound a bit like that other instructor Jim McClain with the 8 step swing where he had you get the club in specific positions on the back and downswing. His method has been denounced by quite a number of top teachers who understand that it is the downswing which is the most important and like Ben Hogan who had a flat swing, he kept his arms in contact with his body and had a body swing and was not handsie at all.

i guess ben hogan and sam snead missed that day when the pro told them not to take the club inside. as long as you keep your body angles, it really doesn't matter where you take the club, your pivot and centripetal force will send the arms where they need to go. all that backswing plane stuff is literally unnecessary.